Pull request: beta client squashed

Merge in DNS/adguard-home from beta-client-2 to master

Squashed commit of the following:

commit b2640cc49a6c5484d730b534dcf5a8013d7fa478
Merge: 659def862 aef4659e9
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Dec 29 19:23:09 2020 +0300

    Merge branch 'master' into beta-client-2

commit 659def8626467949c35b7a6a0c99ffafb07b4385
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Dec 29 17:25:14 2020 +0300

    all: upgrade github actions node version

commit b4b8cf8dd75672e9155da5d111ac66e8f5ba1535
Author: Vladislav Abdulmyanov <v.abdulmyanov@adguard.com>
Date:   Tue Dec 29 16:57:14 2020 +0300

    all: beta client squashed

Dockerfile

@@ -18,6 +18,7 @@ RUN apk --update --no-cache add \
     gcc \
     git \
     npm \
+    yarn \
   && rm -rf /tmp/* /var/cache/apk/*
 
 WORKDIR /app
@@ -26,6 +27,7 @@ COPY . ./
 
 # Prepare the client code
 RUN npm --prefix client ci && npm --prefix client run build-prod
+RUN yarn --cwd client2 build
 
 # Download go dependencies
 RUN go mod download